LWW/CCNQ LWWJ306-08 March 7, 2007 23:32 Char Count= Crit Care Nurs Q Vol. 30, No. 2, pp. 166–180 Copyright c 2007 Wolters Kluwer Health | Lippincott Williams & Wilkins Practical Cardiac Auscultation Daniel M. Shindler, MD, FACC This article focuses on the practical use of the stethoscope. The art of the cardiac physical exam- ination includes skillful auscultation. The article provides the author’s personal approach to the patient for the purpose of best hearing, recognizing, and interpreting heart sounds and murmurs. It should be used as a brief introduction to the art of auscultation. This article also attempts to illustrate heart sounds and murmurs by using words and letters to phonate the sounds, and by presenting practical clinical examples where auscultation clearly influences cardiac diagnosis and treatment. The clinical sections attempt to go beyond what is available in standard textbooks by providing information and stethoscope techniques that are valuable and useful at the bedside. Key words: auscultation, murmur, stethoscope HIS article focuses on the practical use mastered at the bedside. This article also at- T of the stethoscope. The art of the cardiac tempts to illustrate heart sounds and mur- physical examination includes skillful auscul- murs by using words and letters to phonate tation. Even in an era of advanced easily avail- the sounds, and by presenting practical clin- able technological bedside diagnostic tech- ical examples where auscultation clearly in- niques such as echocardiography, there is still fluences cardiac diagnosis and treatment. We an important role for the hands-on approach begin by discussing proper stethoscope selec- to the patient for the purpose of evaluat- tion and use. ing and reassessing cardiac status. Knowing the cardiac history, monitoring the pulse and CHOOSING A STETHOSCOPE blood pressure, and listening to the heart and lungs are integral parts of nursing care. Proper It has been stated that proper auscultation use of the stethoscope is still relevant and im- of the heart depends less on what is around portant to patient care. This article provides the ears and more on what is between the the author’s personal approach to the patient ears. Nevertheless, there are certain easily for the purpose of best hearing, recognizing, recognized features that make a stethoscope and interpreting heart sounds and murmurs. It more capable of transmitting heart sounds to should be used as a brief introduction to the the ears. art of auscultation. Although there are many The cardiac stethoscope requires both a excellent audiovisual aids to auscultation, the bell and a diaphragm to transmit the full spec- cardiac examination should be honed and trum of heart sounds. The difference between the two is that the bell allows low-frequency sounds. The diaphragm filters those out when necessary. Both are used as needed to al- From the Departments of Medicine and low detection of all auditory aspects of heart Anesthesiology, UMDNJ Robert Wood Johnson sounds and murmurs. Medical School. There are cardiac stethoscopes that do not This article was prepared with the financial support have a bell. The bell effect is created by light of 3M. pressure on a specially designed stethoscope Corresponding author: Daniel M. Shindler, MD, FACC, diaphragm. When the stethoscope was first UMDNJ Robert Wood Johnson Medical School, 125 Pa- terson St, New Brunswick, New Jersey 08901 (e-mail: invented, there was no diaphragm, just a bell. [email protected]). The diaphragm effect could still be created 166 LWW/CCNQ LWWJ306-08 March 7, 2007 23:32 Char Count= Practical Cardiac Auscultation 167 Figure 1. 3M Littmann Electronic Stethoscope Model 3000 with ambient noise reduction. by firm pressure on the skin to stretch it, re- justment of this angle to permit forward tilt- sulting in a makeshift temporary diaphragm. ing to align with the external ear canal and We still use this bell-push technique in every to create a complete seal that excludes am- patient. Examples for using the bell and the bient noise. A good habit to try to optimize diaphragm appropriately are presented in sub- this angle at the onset of auscultation con- sequent sections. sists of moving the head up and down in an Electronic stethoscopes can change filter exploratory manner while listening for im- frequency settings to toggle between bell proved audibility of heart sounds. Carrying a and diaphragm modes. New electronic stetho- stethoscope around by stuffing it into a labo- scopes with ambient noise reduction such as ratory coat pocket may change and misalign the Littmann Model 3000 (Fig 1) reduce dis- this critical angle. tracting ambient noise through noise cancel- Earpieces should feel comfortable. The fit lation rather than just filtering, so the heart should be snug without causing discomfort sounds remain unaffected and can actually be when used for prolonged periods of time. An selectively amplified. earpiece can be too large, allowing ambient Tubing should be kept comfortably short noise to enter. It can also be too small, too soft, (to better hear high-pitched heart sound com- or applied with too great a pressure—making ponents). The tubing should remain long it rest too deeply in the ear canal, with the enough to allow a comfortable listening pos- earpiece aperture partly or even completely ture. This is determined to some degree by the occluded. A common mistake is to choose ear- listener’s height, arm length, ability to bend pieces that are too small and enter too far. The the lower back, and degree of personal will- ear canal should be occluded, not invaded. ingness to lean over patients from the right Larger, looser-fitting earpieces can be made to side. fit more snugly during auscultation, if needed, Because of the anatomy of the ear canal, the by pressing the arms of the stethoscope to- angle of direction of earpieces is very impor- gether with the free hand. Listening from the tant. The external ear canal travels toward the right side of the patient keeps the stethoscope eardrum at an anterior angle. A good stetho- in a relatively straight line from the ears to the scope has angled earpieces to allow easy ad- chest. LWW/CCNQ LWWJ306-08 March 7, 2007 23:32 Char Count= 168 CRITICAL CARE NURSING QUARTERLY/APRIL–JUNE 2007 PROPER CARE AND CLEANING OF interfere significantly with auscultation. Faint STETHOSCOPES sounds are masked by louder sounds. The loud sound does not even have to coincide The stethoscope is a medical tool. As such, with the faint sound. The ear instinctively it should be kept clean and regularly disin- tunes to the louder sound and ignores the fected to prevent spreading infection from pa- fainter sound. Proper auscultation technique tient to patient. Earpieces should be periodi- requires listening to one thing at a time. Faint cally inspected for cracks and for earwax ac- sounds require concentration. They should be cumulation. Tubing should also be visually in- listened to (without loud distractors) for as spected for cracks on a routine basis. Leaks in long as necessary. This allows the ear to be- the tubing due to cracks can also be detected come attuned to the full intensity of that par- by blowing into one earpiece while the other ticular sound level. Sometimes it also helps is obstructed. The absence of leaks can be fur- to close one’s eyes. Auscultation cannot be ther sought by abruptly breaking the seal of a hurried examination. The period of time the stethoscope bell with the skin during rou- necessary for proper examination will (hope- tine auscultation. Rapid removal of the bell fully) progressively decrease with experience. should elicit a pressure sensation in the ear Electronic stethoscopes with ambient noise when the tubing is intact. reduction are also available. They may dramat- ically improve the diagnostic yield of an aus- EXAMPLES OF BELL AND cultatory examination in a noisy environment DIAPHRAGM USE such as a moving ambulance, or a busy emer- gency department. As a rule, the bell is held lightly, and the diaphragm is pressed firmly against the skin EXAMINATION TECHNIQUE of the chest wall. The examiner should be- come adept at applying the stethoscope bell The patient is usually approached from the with as little pressure as possible. The pres- right side and the cardiac examination always sure should be no more than what is required begins with proper positioning of the patient. to create a seal to exclude ambient noise. This The patient should be positioned, and the ex- enhances the faint low-frequency vibrations amination bed or table should be adjusted to from ventricular and atrial gallops. As already allow sequential examination of the patient in mentioned, firm pressure with the bell makes the sitting, recumbent, and left lateral decu- the stethoscope behave like a diaphragm by bitus positions. Sitting positions include up- stretching the skin and making it filter heart right, reclining back at an approximately 45 sounds in the way a rigid diaphragm does— degree angle, and any other angle that opti- by damping vibrations. The high-pitched mur- mizes neck vein inspection. Additional patient murs of aortic regurgitation and some cases positions during advanced dynamic ausculta- of mitral regurgitation are better heard with tion may include standing and squatting, face the use of the diaphragm to filter out the down on the bed, and leaning forward while low-frequency components of other distract- standing or sitting. Both the examiner and the ing heart sounds. The diaphragm is pressed patient must be comfortable. Room temper- very firmly against the skin for this purpose. ature should be appropriate for the patient’s state of dress. The patient should be properly AMBIENT NOISE gowned so that the skin of the chest wall can be reached by the examiner without having to The room should be made as quiet as possi- fumble with the patient’s clothing.